Then there are platonic partnerships between artists who are sublimely simpatico: Josef von Sternberg and Marlene Dietrich. George Cukor and Katharine Hepburn. Quentin Tarantino and Uma Thurman.

But few current duos have proven as durable as Joe Wright, a brash purveyor of visual panache, and Keira Knightley, the stunner who ranks among Hollywood's most bankable female talents.

Opening Friday is their third and most daring collaboration, a sumptuously audacious adaptation of Anna Karenina that sets most of Tolstoy's chronicle of love and betrayal among Russia's 19th-century aristocracy inside a decaying theater. Considering that scenes include a heart-stopping horse race at full speed across a stage, it is little wonder that the adjective "bold" figures heavily in early reviews.

The British twosome - a self-proclaimed show-off who got his start at a puppet theater owned by his parents and a child performer who came of age as a soccer player in 2002's Bend It Like Beckham - for some reason gravitate toward literary-based period pieces. Not that Wright would describe them that way. "I like to think of them as being fantasies," he says. "I'm not interested in historical re-enactment. They allow us to dream and think in more expressive ways."

Wright declares his most frequent leading lady to be "my sister in celluloid," and the sibling-like connection that was forged in 2004 during the making of an emotionally unbound interpretation of Jane Austen's Pride & Prejudice appears to have inspired some of their best work.

"It feels like we've grown up together," says the filmmaker, 40, whose London home is just a few doors down from where 27-year-old Knightley resides. "We've seen each other through some good times and some bad times, and that's a lovely process. I like the idea of working with someone who has seen me at my weakest and also with success."

Not that they always agree. Both have been upfront about their heated debates. That includes much discussion over which role Knightley would take in their second effort, the 2007 World War II drama Atonement, which earned seven Oscar nominations, including best picture.

Wright's preference for glamorous Cecilia, whose posh mannerisms are in stark contrast to Knightley's girlish portrayal of free-spirited Elizabeth Bennet in Pride & Prejudice, won out and allowed the stylish actress to make a lasting impression in a showstopper of an emerald-green gown.

"He understands what I'm talking about," the actress says. "We do argue occasionally, and like siblings, you kind of know that you have to get over the argument because you're not going to stop being siblings. And so it's never the end of the world when you argue. There is a trust in the fact that underneath anything that is going on, you're still going to love each other."

She stands by her Mr. Wright even if her characters are sometimes subjected to abuse and worse. "We have worked three times, and he has killed me twice," she observes. "We've done three commercials, and he had me beaten up in one of them."

Adds Wright, "But you've made a lot of love, though."

She nods. "A lot of love."

But don't get Knightley started on the countless hours of rehearsal time she invested in learning Anna Karenina's intricate dance numbers, in which arms intertwine and flutter provocatively.

"Keira still hates me for that," says Wright with a wicked laugh.

"It was worth it," she concedes, "even though he cut another dance sequence that took ages."

Parallels in their private lives abound. Both have struggled with dyslexia. Both became involved in long-term relationships and subsequently broke up with cast members from Pride & Prejudice: Knightley with Rupert Friend (TV's Homeland) and Wright with Rosamund Pike (Jack Reacher with Tom Cruise, out Dec. 21).

And they each have entered a settling-down phase. In 2010, Wright married Anoushka Shankar, a Grammy-nominated musician and daughter of celebrated sitarist and Beatles associate Ravi Shankar. Their son, Zubin, turns 2 in February. Knightley became engaged to her own musician, James Righton of the Klaxons, in May.

Their influence on each other even extends into their off-hours, such as in wardrobe choices. Today, they are a vision in black (her Celine shift) and blue (his natty dark denim suit).

"I'm wearing John Pearse," says Wright, dropping the name of the tailor who once co-owned the notorious '60s boutique Granny Takes a Trip. "Jacqueline Durran (the costumer for Pride & Prejudice and Atonement) made an exquisite denim dress for Keira and I was quite jealous of it. I felt I wanted a denim suit. I didn't think a dress would suit me."

Says Knightley, with a saucy smile, "Oh, I don't know ..."

They have come a long way since everyone from Austen cultists to Colin Firth fans (who consider the actor to be the definitive Mr. Darcy) questioned the wisdom of attempting to top the six-part 1995 BBC adaptation of Pride and Prejudice a decade later. Back then, Knightley was known for supporting roles in the first Pirates of the Caribbean adventure and the ensemble comedy Love Actually.

However, Pride & Prejudice proved to be her entree into the big leagues after it earned her her first Oscar nomination. Wright's reward? A brand-new career path. His feature-directing debut allowed him to move on from the TV projects he had been doing in England to being sought after for theatrical movies.

No small feat, Wright notes. "My producer, Paul Webster, on Pride & Prejudice did keep saying to me, 'One in 10 first-time directors get to make another film.' "

Knightley laughs. "Nothing like working under pressure."

He glances fondly at her. "I think I owe my career to Keira, really."

Knightley gently scoffs: "Bull---- you do."

Tim Bevan, whose production company, Working Title, has produced all of Wright's vehicles with Knightley, thinks it is a match made in costume-drama heaven for both parties.

"Joe brings out the best in Keira," he says, while noting that the actress often gets bashed by hometown critics for being a little too one-note. "He can extract an emotional performance out of her that others are unable to do. He treats her with intellectual respect. Every actor has their tricks and looks, and he knocks that out of her. He insists on proper honesty on-set."

Meanwhile, Wright benefits from Knightley's charismatic wattage. "The reason I got him to see her on Pride is that I pointed out that she is a movie star, an English movie star," Bevan says. "What that does for him is to get these movies made."

While Wright likes to say that Knightley was the one who brought up the possibility of doing Anna Karenina together while making Atonement, she claims it wasn't so simple.

"We were having a discussion of great female characters," she says. "This was one. He remembers me reading it during Atonement. I thought I had read it earlier. But Anna Karenina was at the forefront of my mind. We also discussed Hedda Gablerand Antigone."

She says Wright called her two years later and asked, "Do you remember that talk? Do you fancy doing it?"

Both feel she is the perfect age now to pull off a role as mature as an aristocratic woman who tosses away her marriage and her standing in society after falling for a dashing philanderer.

"Keira was 18 when we made Pride, and when we made Atonement, she was 21," he says. "A lot has happened to her since, and that informs your understanding of the world, eventually. Keira is a proper grown-up now, and it really is a proper grown-up performance. She was incredibly powerful when she was 18 and 21, but it wasn't as focused or as direct. And that's changed. And I've changed, too."

Suddenly, there is a knock on the door, and a tray is brought in stacked with plates of sushi and bowls of miso soup.

Continuing his thought about change, Wright jokes, "I now eat sushi."

Says Knightley, "You now get sushi brought to you."

Wright does want to clarify a wrong impression that arose during the film's premiere at the Toronto Film Festival. "Everyone keeps asking me, 'Is she your muse?' She is not my muse. My wife is my muse."

"That is a very good muse to have," Knightley concurs.

Still, he can't help but act somewhat peeved when the actress discusses an upcoming project, a reboot of the Jack Ryan franchise (including The Hunt for Red October and Patriot Games) in which Chris Pine takes over the role of author Tom Clancy's CIA agent, previously played by Alec Baldwin, Harrison Ford and Ben Affleck. Knightley is cast as Ryan's wife.

Wright can hardly wait to inquire, "Who is directing?"

"Kenneth Branagh," she answers, "who is also playing the baddie."

Wright, who next tackles a stage revival of Trelawny of the "Wells" at London's Donmar Warehouse, is amused by his own overreaction to the news. "I get a little bit jealous when I hear that. You are supposed to wait for me in a field of lavender."